The present disclosure relates to a display apparatus and a display method, and, in particular, to a display apparatus and a display method in which the length of the blanking interval of a video signal can be adjusted.
In related art, there is a display apparatus in which various types of operational buttons or the like are displayed on a display in such a way that a touch panel is superimposed on the display or that the display is integrated with the touch panel, and which enables operational input to be performed on the display by detecting the operation of a user who touches the display.
Since such a display apparatus does not need operational buttons as hardware, the display apparatus is widespread in portable information terminals, such as a tablet computer and a smart phone.
As a touch panel operation detection method used for the portable information terminals, a capacitance type has been known which has a comparatively simple configuration and the power consumption of which is low.
Here, the basic principal of a capacitance type touch panel is described with reference to FIGS. 1A to 3B.
FIGS. 1A and 2A show the basic configurations of the capacitance type touch panel, and FIGS. 1B and 2B are the respective equivalent circuits thereof.
That is, in the capacitance type touch panel, a dielectric material D is interposed between a pair of detection electrodes E1 and E2 which are arranged to face each other, thus a capacitance device C1 is formed. One end of the capacity device C1 is connected to an Alternating-Current (AC) signal source (drive signal source) S, and the other end P is connected to a voltage detector DET while being grounded via a resistor R.
If a finger of the user comes into contact with (or approaches) the detection electrode E2 as shown in FIG. 2A, a capacity device C2 which is formed by the finger is added to the capacity device C1 in series.
FIGS. 3A and 3B show the AC square wave Sg of a predetermined frequency which is applied from the AC signal source S to the detection electrode E1, and an output waveform (touch detection signal Vdet) which is detected using the detection electrode E2 according thereto. In addition, the AC square wave Sg corresponds to a touch detection drive signal Vcomt which will be described later.
As shown in FIGS. 1A and 1B, in a state in which a finger does not come into contact with the detection electrode E2, current I0 based on the capacitance value of the capacity device C1 flows in accordance with the charge and discharge of the capacity device C1. The potential waveform of the other end P of the capacity device C1 at this time is, for example, the waveform V0 shown in FIG. 3A, and this is detected using the DET.
Meanwhile, as shown in FIGS. 2A and 2B, in a state in which a finger comes into contact with the detection electrode E2, currents I1 and I2 respectively flow in accordance with the charge and discharge of the capacity devices C1 and C2. The potential waveform of the other end P of the capacity device C1 at this time is, for example, the waveform V1 shown in FIG. 3A, and this is detected using the DET. At this time, the potential of a point P is partial pressure potential which is determined based on the value of the currents I1 and I2 which flow through the capacity devices C1 and C2. Therefore, the value of the waveform V1 is smaller than that of the waveform V0 in the non-contact state. Here, the DET implements the touch detection in such a way as to determine the non-contact state if the detected voltage is equal to or higher than a predetermined threshold voltage Vth and determine the contact state if the detected voltage is lower than the predetermined threshold voltage Vth.
In addition, when the touch panel is combined with the display, the configuration can be simplified by using the common electrode for the display as one of the above-described pair of detection electrodes E1 and E2 (for example, refer to JP-A-2009-244958).